chore: bump version (#299)

Author: lgray

src/fastjet/version.py

@@ -2,7 +2,7 @@
 
 import re
 
-__version__ = "3.4.2.0"
+__version__ = "3.4.2.1"
 version = __version__
 version_info = tuple(re.split(r"[-\.]", __version__))